Intracellular HIV-1 Gag localization is impaired by mutations in the nucleocapsid zinc fingers.

Boyan Grigorov,Marylène Mougel,Fatima Smagulova,Didier Décimo,Jean-Luc Darlix,Christine Péchoux,Delphine Muriaux

doi:10.1186/1742-4690-4-54

Abstract

BackgroundThe HIV-1 nucleocapsid protein (NC) is formed of two CCHC zinc fingers flanked by highly basic regions. HIV-1 NC plays key roles in virus structure and replication via its nucleic acid binding and chaperoning properties. In fact, NC controls proviral DNA synthesis by reverse transcriptase (RT), gRNA dimerization and packaging, and virion assembly.ResultsWe previously reported a role for the first NC zinc finger in virion structure and replication [1]. To investigate the role of both NC zinc fingers in intracellular Gag trafficking, and in virion assembly, we generated series of NC zinc fingers mutations. Results show that all Zinc finger mutations have a negative impact on virion biogenesis and maturation and rendered defective the mutant viruses. The NC zinc finger mutations caused an intracellular accumulation of Gag, which was found either diffuse in the cytoplasm or at the plasma membrane but not associated with endosomal membranes as for wild type Gag. Evidences are also provided showing that the intracellular interactions between NC-mutated Gag and the gRNA were impaired.ConclusionThese results show that Gag oligomerization mediated by gRNA-NC interactions is required for correct Gag trafficking, and assembly in HIV-1 producing cells and the release of infectious viruses.

Highlights

The HIV-1 nucleocapsid protein (NC) is formed of two CCHC zinc fingers flanked by highly basic regions
The retroviral Gag polyprotein precursor is formed of three essential domains, namely the matrix (MA), the capsid (CA) and the nucleocapsid (NC), which upon protease mediated processing of Gag constitute the architecture of the infectious mature viral particle
We explored the influence of the NC zinc fingers in HIV-1 assembly by analyzing intracellular Gag and genomic RNA (gRNA) localization, Gag/membrane association and virion morphogenesis

Summary

Introduction

The HIV-1 nucleocapsid protein (NC) is formed of two CCHC zinc fingers flanked by highly basic regions. The three Gag domains contain the critical determinants that orchestrate virus assembly in the infected cell, via membrane-MA, CACA and NC-gRNA interactions [2,3,4,5,6,7,8]. In the case of HIV-1, MA is myristoylated and contains basic amino acids within its N-terminus required for Gag-membrane binding and determinants that interact with the cellular adaptator proteins AP-3 and AP-2. These AP proteins contribute to the intracellular transport of Gag to endosomal compartments and retroviral budding [9,10,11]. The CA molecules form the outer shell of the viral (page number not for citation purposes)

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Conclusion